Glycemic Index simply ranks foods on how quickly they affect glucose levels in the blood stream.Developed in Toronto in the 1980s to help doctors prescribe diets for diabetics, foods that quickly elevate blood sugar levels have a high glycemic index. Foods that increase blood sugar slowly have lower glycemic indices.

In addition to Diabetics, Athletes also tend to be highly aware of blood glucose levels to both prepare for and recovery from intense exercise. Regular exercisers can also benefit from an awareness of blood sugar levels, however, because the of the effect cortisol has on glucose metabolism when you are low on blood sugar.

You might think that you’re doing yourself a favor skipping lunch, when in fact, doing so triggers your body to generate more cortisol.

Cortisol … the “your under stress hormone” counteracts Insulin production and reduces the metabolism of glucose. The result of this is disproportionately more fat storage in anticipation of famine! Additionally, the increased Cortisol increases appetite so you’re more likely to overeat at your next meal!

It would be great if you could simply categorize carbohydrates into glycemic index groups that fit nicely within some saccharide category, but the truth is, it’s somewhat of a frustrating memorization exercise.

Take roots. Carrots & yams (both simple carbohydrate foods) have relatively low GIs of 39 and 51, respectively, while potatoes have GIs as high as 85! The difference here is that potatoes are very starchy.

So, starchy means high GI then?

Not quite. Plenty of other starchy carbs, like Oats, Bran, Rye and Barley are actually quite low in GIs scoring in the 20s and 30s. Similarly, wheat and most rices also score fairly low (50s), while brown rice pasta has an exceptional and soaring 91!

And then there’s fruit. Unless I’ve missed something, no fruits are starchy. They’re fibrous and watery, but not starchy. But here’s the rub: some fruits have very low GIs, like grapefruit (25), plums (39), and apples (38); and some fruits have moderate GIs, like mangos (56), apricots (57), and raisins (64). Why then, does watermelon have a sky high GI of 72?

Attempting to solve this mystery steps in Glycemic Load.

As it turns out, part of the reason why inconsistencies exist across the simple to complex carbs GI spectrum is related to quantity consumed. For example, a single piece of hard candy (nearly all sucrose) will trigger a smaller glucose response than a bite of a banana. But if you consume 2 cups of each, the candy outpaces the banana quite quickly!

What’s more, Net Carbs also have a role. As mentioned above, the fiber content will affect digestion speed, which, in turn, effects blood sugar fluctuations. So, in the late ‘90s, the Glycemic Load became a more popular way to determine food effect on blood sugar, defined as the percentage of GI times Net Carbs:

Glycemic Load = Glycemic Index / 100 x Net Carbs

Got that? Well, before you start looking for a smart phone app to calculate GL, have no worries, many nutritionists have simply done the math for you with tables they’ve built themselves. In fact, one of my all time favorite nutrition sites, NutritionData.com doesn’t list GI at all, but instead lists an Estimated Glycemic Load number for most of it’s nutritional listings. The values are estimated simply because complete data on GI and Net Carb values simply hasn’t yet been compiled for all foods.

What you also need to know about GI vs GL numbers is that a high GL number could be a low GI Number:

Withstanding GL wizardry, one food category that emerges consistently high in the GI tables is highly refined grains, particularly those in baked goods. French bread, cookies, cakes, doughnuts, rice cakes, and many breakfast cereals ALL SCORE very high on GI tables.

Not only do they trigger a short, spiky bust in glucose, but they are also reasonably ‘empty’ calories with very few micronutrients (vitamins and minerals). To make matters worse, they frequently include added sugars to make an already unhealthy food even more caloric. Sometimes inclusive of saturated and/or hydrogenated fats as well, and well, these products are really quite evil to health and fitness professionals.

The Carbohydrate Conundrum: What to do?

With all of this going on, it’s no wonder the general public is confused about carbohydrates and their dietary relevance. Here then is my professional recommendation on the topic.

First, if you are diabetic, follow your doctor’s orders, not mine.

For all the rest of us:

The easiest way to defuse most of your concerns about carbohydrates is simply to exercise more! Not only will you metabolize more calories in doing so, but other hormones involved with exercise and exercise recovery help keep cortisol and insulin balanced.

Recognize that carbohydrates are, above all else, your body’s primary fuel source. While it’s true that your body always metabolizes a blend of carbohydrates, fats, and protein, carbohydrates are your primary fuel source. If your engine is just idling, back off on the fuel!

If you are sedentary, you need very complex few carbohydrates. Most of your energy will come from stored energy sources (glycogen and body fat). Eliminate most complex carbohydrates from your diet to avoid gaining body fat.

If you are active, you need some complex carbohydrates. Try to get most of your complex carbohydrates early in the day, typically before 2:00 PM. Switch to mostly simple carbohydrates after that.

If you are regularly exercising, or an athlete, you need a LOT more carbohydrates. Get most of your complex carbs early in the day, but do include moderate quantities later in the day. Don’t hesitate to include higher amounts in your diet if you have a high intensity exercise event the following morning.

Eat a wide variety of and large quantities of fruits and vegetables. Follow the seasonally available produce and you’ll get plenty of variety. Make sure you get at wide variety of color in your diet. A lot of people miss out on the yellows: squash, yams, yellow peppers.

When choosing complex carbohydrates, focus on whole grains, and high fiber sources. Steel cut oats, whole wheat, and wild rice are good examples.

Always avoid or minimize highly refined grains, particularly those with added sugars. MOST of the grocery store bakery fits into this category: cookies, cakes, pies (it’s the crust), french bread, muffins, and doughnuts. What’s worse is that many of these will also include partially hydrogenated fats.

Avoid or eliminate them if you are serious about your health.

Heart disease is still the #1 cause of death for men and women in America and these fats are deadly